(1) Field of the Invention
The present invention relates to a multimedia signal processing apparatus (equipment) suitable for use in an apparatus, such as a switching apparatus (exchange) to be connected to a node (higher-rank node) constituting a common public switched network or mobile (radio) communications network, which is required to conduct needed signal processing with respect to signals (multimedia signals) to be interchanged with a higher-rank node according to classification (type) of communication service.
(2) Description of the Related Art
FIG. 23 is an illustrative view showing one example of the existing public switched network. In the usual way, as FIG. 23 shows, a public switched network (which will hereinafter be referred to simply as a “public network”), designated generally at reference numeral 100, has been constructed basically in the form of a hierarchical structure called “tree network”, because of the economic impracticality of accommodating each of the nationwide subscriber terminals (telephones, personal computers, facsimiles, and other equipment) in a switching apparatus (switching exchange; node) installed in its neighboring area for connecting the switching exchanges of the respective areas entirely into a mesh-like configuration.
That is, taking Japan for instance, the whole of Japan is divided into some large areas (regional center areas; RAs) 101 each for installation of one regional center (RC) 110, with each of the regional center areas 101 being further divided into district center areas (DAs) 102 each for installation of one district center (DC) (sectional centers) 120, and even each of the district center areas 102 is additionally divided into toll center areas (TAs) 103 each for installation of one toll center (TC) (primary center) 130, with each of the toll center areas 103 being still additionally divided into terminal station areas 104 each for installation of one end office (EO) 140.
In addition, exchanges (centers, offices) pertaining to a lower-rank hierarchy are connected to an exchange pertaining to a higher-rank hierarchy to set up a star network (for example, the end offices 140 are accommodated in the toll center 130, and the toll centers 130 are accommodated in the district center 120, and further the district centers 120 are accommodated in the regional center 110), with the regional centers 110 being connected through basic circuits to each other, thus establishing the public network 100.
With such a configuration, in the existing public network 100, for example, in the case of long-distance toll call such as between Tokyo and Osaka, the calls starting from the end offices 140 are collected stepwise in the order of the toll centers 130, the district centers 120 and the regional centers 110 to be transmitted to the regional centers 110 accommodating the target end offices (call destinations) 140. That is, call collection and delivery is made along the “tree network”, which enables efficient call transmission.
Meanwhile, for example, as service requests (signal processing requests) such as a request for call connection to a switching apparatus connected to a higher-rank hierarchy exchange (higher-rank node), there have been known a plurality of types of service classifications corresponding to various communication service modes, such as voice communications, packet communications, data communications using ISDN (Integrated Services Digital Network) and facsimile (FAX) communications, with the service classifications being not settled according to call. Incidentally, the “service classification” signifies the classification of a communication protocol peculiar to a communication service.
Furthermore, in a case in which there is a need for a switching apparatus to handle signals (multimedia signals) pertaining to these various service classifications, since this switching apparatus is required to function additionally as a system (multimedia signal processing apparatus) capable of dealing with multimedia signals, for example as shown in FIG. 24, packages (PKG) 200 each dedicated to a service classification, whose quantity is set to handle the maximum traffic (the maximum number of calls) estimated according to service classification, are mounted at every service classification (expressed by #A, #B, #C, and others) so that, in response to each service request from a higher-rank node 400, the package 200 corresponding to that service classification is selected to conduct the processing of a call (signal processing) with respect to the service request.
For example, when the higher-rank node 400 issues a service request for the service classification #A, the switching apparatus makes a decision/determination to the call service classification on the basis of information included in the received service request through the use of a service determining section 302 under control of a call control section 301 in a main control section 300, and further selects an idle package 200 of the packages 200 for the service classification #A as, for example, so-called incoming trunk/outgoing trunk on the basis of package mounted state management data 330 under management of a package mounted state managing section 303 and conducts the call processing.
Likewise, in response to a service request for another service classification #B or #C, the idle package 200 corresponding to the service classification #B or #C is seized or captured for conducting the call processing.
However, in the case of the above-mentioned arrangement, since the package 200 corresponding to a service request from the higher-rank node 400 is fixed according to service classification, a need for previous mounting of packages 200 capable of dealing with the estimated maximum traffic exists, which increases the scale of the switching apparatus. In addition to this problem, in a case in which calls exceed the maximum traffic (overload traffic), the foregoing configuration and processing leads to call loss (generation of rejection of newly arrived call).